CA1241910A - Radiant energy burner - Google Patents
Radiant energy burnerInfo
- Publication number
- CA1241910A CA1241910A CA000472606A CA472606A CA1241910A CA 1241910 A CA1241910 A CA 1241910A CA 000472606 A CA000472606 A CA 000472606A CA 472606 A CA472606 A CA 472606A CA 1241910 A CA1241910 A CA 1241910A
- Authority
- CA
- Canada
- Prior art keywords
- fabric
- support
- burner
- sleeve
- radiant energy
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
- F23D14/12—Radiant burners
- F23D14/14—Radiant burners using screens or perforated plates
- F23D14/145—Radiant burners using screens or perforated plates combustion being stabilised at a screen or a perforated plate
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Gas Burners (AREA)
Abstract
RADIANT ENERGY BURNER
Abstract of the Disclosure A radiant energy burner having a combustion element composed of a generally cylindrical foraminous metal support or screen, and a woven fabric formed of substantially continuous ceramic fibers is disposed on the outer surface of the support. The end portions of the fabric are connected to the support while the por-tion of the fabric located between the connected end portions is free of attachment to the support. A
blower is used to supply a gaseous fuel mixture through the support and fabric and an igniter is located on the outer surface of the fabric to ignite the fuel mixture on the outer surface of the fabric.
Abstract of the Disclosure A radiant energy burner having a combustion element composed of a generally cylindrical foraminous metal support or screen, and a woven fabric formed of substantially continuous ceramic fibers is disposed on the outer surface of the support. The end portions of the fabric are connected to the support while the por-tion of the fabric located between the connected end portions is free of attachment to the support. A
blower is used to supply a gaseous fuel mixture through the support and fabric and an igniter is located on the outer surface of the fabric to ignite the fuel mixture on the outer surface of the fabric.
Description
-1- 12~1910 RADIANT ENERGY BURNER
Background of the Invention Radiant energy burners employ a combustion element which is permeable to the gaseous fuel and the fuel is burned in a flameless type of combustion on the outer surface of the element to principally emit radi-ant energy. In burners of this type, it is important to control the porosity and back pressure of the com-bustion element in order to obtain the proper combus-tion efficiency and minimize the possibility of "blowback" or flame lifting from the surfce of the burner.
In the past, a form of radiant combustion element has consisted of an inner metal screen covered with a layer of randomly disposed short ceramic fibers. Elements of this type have been produced by immersing the screen in a molding tank containing a liquid slurry of the ceramic fibers and then drawing a vacuum through the screen, with the result that the fibers are deposited as a layer on the screen. The resulting vacuum-formed layer of ceramic fibers is fragile and is highly susceptible to damage during shipment and handling.
During use, the short fibers in the vacuum formed layer tend, with time, to dissociate which results in the combustion element having a non-uniform porosity, thereby decreasing the efficiency of the combustion and the useful life of the burner.
Furthermore, if the vacuum formed fibrous coating is broken away, either by damage or during usage, an outage can result in which a flame sensor will shut down the system due to a significant change in combustion pattern. While an outage is not a dan-gerous situation, it is a nuisance problem.
- -2- ~241910 To provide protection for the fragile vacuum formed coating, attempts have been made in the past to enclose the combustion element in an outer protective sleeve, such as described in United States Patent No.
3,275,497 and 3,179,156. However, the use of an outer protective screen substantially reduces the efficiency of the radiant heating operation and adds unnecessary cost.
Summary of the Invention The invention is directed to a radiant energy burner having an improved combustion element. In the preferred form, the combustion element comprises a generally cylindrical metal screen or support, and a woven fabric sleeve composed of continuous ceramic fibers is disposed around the screen. The ends of the sleeve are secured to the metal support, while the central portion of the sleeve is free of attachment.
In use, a blower supplies a gaseous fuel mixture to the interior of the cylindrical support and the mixture flows outwardly through the support and fabric where it is combusted on the outer surface of the fabric to emit primarily a radiant form of energy.
As the woven ceramic fabric is flexible and not brittle, the combustion element is extremely dur-able and can be handled without damage.
Because the fabric is composed of continuous fibers, there is no loss of fibrous content during usage, with the result that useful life is prolonged.
Also, the porosity of the fabric will remain substanti-ally the same during service which enhances uniform combustion.
The woven fabric is available in different grades to obtain the desired porosity depending upon the particular application or use.
. .
_3_ ~Z~l~10 As the woven fabric is not secured throughout its length to the metal support, but only at its end portions, the difference in coefficient of expansion between the fabric and the metal screen is not a life limiting factor. The fabric is capable of compensating for the greater expansion of the screen at elevated temperatures. This is a substantial improvement over a vacuum formed ceramic layer which is attached through-out its length to the supporting metal screen. In this latter system, due to the difference in coefficient of expansion between the two materials, stresses can be set up in the vacuum formed coating causing cracking and rupture of the coating.
Other objects and advantages will appear in the course of the following description.
Description of the Drawings The drawings illustrate the best mode presently contemplated of carrying out the invention.
In the drawings:
Fig. 1 is a side elevation of the combustion element for a radiant energy heater with parts broken away in section;
Fig. 2 is a transverse section taken along line 2-2 of Fig. l; and Fig. 3 is a fragmentary enlarged section showing the connection of the fabric sleeve to the metal support.
Description of the Illustated Embodiment Fig. 1 illustrates a combustion element 1 to be used in a radiant energy burner. The combustion element includes a mounting flange 2 which is adapted to be connected to a suitable supporting structure or housing and is attached to inlet conduit 3. A gener-ally cylindrical foraminous metal support or screen 4 is secured around the end of conduit 3 and extends out-' _4_ ~4~
wardly from mounting flange 2. An end closure 5 issecured within the outer end of the cylindrical screen 4 to close off the outer end.
In accordance with the invention, a woven fabric sleeve 6 is located around the screen 4. Sleeve 6 is formed of continuous ceramic fibers capable of withstanding temperatures in excess of 1800F. As an example, the sleeve 6 can be woven from ceramic fibers sold under the trademark of Nextel (3M Company) which are continous polycrystalline metal oxide fibers, with the metal oxides consisting by weight, of 62% aluminum oxide, 14% boron oxide, and 24% silicon dioxide.
The ends of sleeve 6 are connected to the screen 4 by connecting assemblies indicated by 7. Each connecting assembly 7 includes a conventional metal strap 8 which is located within a ring-like sleeve of ceramic fabric 9. The sleeve 9 can be composed of the same material as the sleeve 6.
The ring-like sleeve 9 is provided with an opening and the free end of the tie strap 8 extends through the opening. After the tie strap 8 is firmly clamped to sleeve 6 the projecting end of the tie strap can be severed at the location of the opening in the sleeve 9 so that the end of the tie strap is not expos-ed. This type ox connecting assembly 7 eliminates direct contact between the metal tie strap 8 and the fabric sleeve 6 and thus minimizes wear of sleeve 6 as the screen and sleeve expand during usage. Further-more, the outer layer of the ring-like sleeve 9 pro-tects the metal tie strap 8 against the high tempera-tures generated during use of the burner.
As best shown in Fig. 3, the connecting assembly 7 located at the outer end of screen 4, adjac-ent end closure 5, is positioned within a groove 10 in the screen 4.
, _5_ 2 9 0 The gaseous fuel mixture, which can be a mixture of a gas, such as natural gas, propane or the like, and air is introduced into the interior of the screen 4 through inlet conduit 3 by a blower which provides the necessary pressure to force the gaseous fuel mixture through the fabric sleeve 6.
The fuel is ignited on the outer surface of sleeve 6 by a standard igniter unit 11. The result is a flameless type of combustion on the outer surface of the woven fabric sleeve 6 which principally results in the emmision of radiant energy.
The radiant burner of the invention can be used in a wide variety of applications, such as space heaters, furnaces, water heaters, and the like. When used with a water heater, the radiant burner would be enclosed within a heating chamber, so that it is not in direct contact with the water to be heated.
The woven ceramic fabric, being a flexible material, provides an extremely durable combustion element which eliminates the problems encountered with the vacuum formed combustion elements, as used in the past.
As a further advantage, the fabric being formed from continuous fibers, eliminates the loss of fibrous content during use with the result that the porosity of the fabric will be maintained substantially uniform during service.
As the sleeve is attached only to the metal support at its end portions, the metal support or screen can move or expand relative to the fabric when exposed to elevated temperatures. This is a substan-tial improvement over the vacuum formed fibrous element in which the fibrous layer is bonded throughout its length to the support. Due to the substantial differ-ence in coefficient of expansion between the ceramic -6- g 9 1 0 fiber material and the underlying metal support in the vacuum formed element, stresses are set up in the fib-rous coating which can result in cracking and ultimate rupture.
Background of the Invention Radiant energy burners employ a combustion element which is permeable to the gaseous fuel and the fuel is burned in a flameless type of combustion on the outer surface of the element to principally emit radi-ant energy. In burners of this type, it is important to control the porosity and back pressure of the com-bustion element in order to obtain the proper combus-tion efficiency and minimize the possibility of "blowback" or flame lifting from the surfce of the burner.
In the past, a form of radiant combustion element has consisted of an inner metal screen covered with a layer of randomly disposed short ceramic fibers. Elements of this type have been produced by immersing the screen in a molding tank containing a liquid slurry of the ceramic fibers and then drawing a vacuum through the screen, with the result that the fibers are deposited as a layer on the screen. The resulting vacuum-formed layer of ceramic fibers is fragile and is highly susceptible to damage during shipment and handling.
During use, the short fibers in the vacuum formed layer tend, with time, to dissociate which results in the combustion element having a non-uniform porosity, thereby decreasing the efficiency of the combustion and the useful life of the burner.
Furthermore, if the vacuum formed fibrous coating is broken away, either by damage or during usage, an outage can result in which a flame sensor will shut down the system due to a significant change in combustion pattern. While an outage is not a dan-gerous situation, it is a nuisance problem.
- -2- ~241910 To provide protection for the fragile vacuum formed coating, attempts have been made in the past to enclose the combustion element in an outer protective sleeve, such as described in United States Patent No.
3,275,497 and 3,179,156. However, the use of an outer protective screen substantially reduces the efficiency of the radiant heating operation and adds unnecessary cost.
Summary of the Invention The invention is directed to a radiant energy burner having an improved combustion element. In the preferred form, the combustion element comprises a generally cylindrical metal screen or support, and a woven fabric sleeve composed of continuous ceramic fibers is disposed around the screen. The ends of the sleeve are secured to the metal support, while the central portion of the sleeve is free of attachment.
In use, a blower supplies a gaseous fuel mixture to the interior of the cylindrical support and the mixture flows outwardly through the support and fabric where it is combusted on the outer surface of the fabric to emit primarily a radiant form of energy.
As the woven ceramic fabric is flexible and not brittle, the combustion element is extremely dur-able and can be handled without damage.
Because the fabric is composed of continuous fibers, there is no loss of fibrous content during usage, with the result that useful life is prolonged.
Also, the porosity of the fabric will remain substanti-ally the same during service which enhances uniform combustion.
The woven fabric is available in different grades to obtain the desired porosity depending upon the particular application or use.
. .
_3_ ~Z~l~10 As the woven fabric is not secured throughout its length to the metal support, but only at its end portions, the difference in coefficient of expansion between the fabric and the metal screen is not a life limiting factor. The fabric is capable of compensating for the greater expansion of the screen at elevated temperatures. This is a substantial improvement over a vacuum formed ceramic layer which is attached through-out its length to the supporting metal screen. In this latter system, due to the difference in coefficient of expansion between the two materials, stresses can be set up in the vacuum formed coating causing cracking and rupture of the coating.
Other objects and advantages will appear in the course of the following description.
Description of the Drawings The drawings illustrate the best mode presently contemplated of carrying out the invention.
In the drawings:
Fig. 1 is a side elevation of the combustion element for a radiant energy heater with parts broken away in section;
Fig. 2 is a transverse section taken along line 2-2 of Fig. l; and Fig. 3 is a fragmentary enlarged section showing the connection of the fabric sleeve to the metal support.
Description of the Illustated Embodiment Fig. 1 illustrates a combustion element 1 to be used in a radiant energy burner. The combustion element includes a mounting flange 2 which is adapted to be connected to a suitable supporting structure or housing and is attached to inlet conduit 3. A gener-ally cylindrical foraminous metal support or screen 4 is secured around the end of conduit 3 and extends out-' _4_ ~4~
wardly from mounting flange 2. An end closure 5 issecured within the outer end of the cylindrical screen 4 to close off the outer end.
In accordance with the invention, a woven fabric sleeve 6 is located around the screen 4. Sleeve 6 is formed of continuous ceramic fibers capable of withstanding temperatures in excess of 1800F. As an example, the sleeve 6 can be woven from ceramic fibers sold under the trademark of Nextel (3M Company) which are continous polycrystalline metal oxide fibers, with the metal oxides consisting by weight, of 62% aluminum oxide, 14% boron oxide, and 24% silicon dioxide.
The ends of sleeve 6 are connected to the screen 4 by connecting assemblies indicated by 7. Each connecting assembly 7 includes a conventional metal strap 8 which is located within a ring-like sleeve of ceramic fabric 9. The sleeve 9 can be composed of the same material as the sleeve 6.
The ring-like sleeve 9 is provided with an opening and the free end of the tie strap 8 extends through the opening. After the tie strap 8 is firmly clamped to sleeve 6 the projecting end of the tie strap can be severed at the location of the opening in the sleeve 9 so that the end of the tie strap is not expos-ed. This type ox connecting assembly 7 eliminates direct contact between the metal tie strap 8 and the fabric sleeve 6 and thus minimizes wear of sleeve 6 as the screen and sleeve expand during usage. Further-more, the outer layer of the ring-like sleeve 9 pro-tects the metal tie strap 8 against the high tempera-tures generated during use of the burner.
As best shown in Fig. 3, the connecting assembly 7 located at the outer end of screen 4, adjac-ent end closure 5, is positioned within a groove 10 in the screen 4.
, _5_ 2 9 0 The gaseous fuel mixture, which can be a mixture of a gas, such as natural gas, propane or the like, and air is introduced into the interior of the screen 4 through inlet conduit 3 by a blower which provides the necessary pressure to force the gaseous fuel mixture through the fabric sleeve 6.
The fuel is ignited on the outer surface of sleeve 6 by a standard igniter unit 11. The result is a flameless type of combustion on the outer surface of the woven fabric sleeve 6 which principally results in the emmision of radiant energy.
The radiant burner of the invention can be used in a wide variety of applications, such as space heaters, furnaces, water heaters, and the like. When used with a water heater, the radiant burner would be enclosed within a heating chamber, so that it is not in direct contact with the water to be heated.
The woven ceramic fabric, being a flexible material, provides an extremely durable combustion element which eliminates the problems encountered with the vacuum formed combustion elements, as used in the past.
As a further advantage, the fabric being formed from continuous fibers, eliminates the loss of fibrous content during use with the result that the porosity of the fabric will be maintained substantially uniform during service.
As the sleeve is attached only to the metal support at its end portions, the metal support or screen can move or expand relative to the fabric when exposed to elevated temperatures. This is a substan-tial improvement over the vacuum formed fibrous element in which the fibrous layer is bonded throughout its length to the support. Due to the substantial differ-ence in coefficient of expansion between the ceramic -6- g 9 1 0 fiber material and the underlying metal support in the vacuum formed element, stresses are set up in the fib-rous coating which can result in cracking and ultimate rupture.
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a radiant energy burner, a combustion element comprising a porous metal support having an inner surface and an outer surface, a flexible woven fabric disposed on the outer sur-face of said support and composed solely of substantially contin-uous polycrystalline metal oxide fibers, connecting means for securing an end portion of said fabric to said support, supply means including a blower to supply gaseous fuel through said sup-port and said fabric, and fuel igniting means disposed adjacent to the outer surface of the fabric to ignite said fuel.
2. The burner of claim 1, wherein said fibers are com-posed by weight of about 62% aluminum oxide, 14% boron oxide, and 25% silicon dioxide.
3. The burner of claim 1, wherein said connecting means comprises a ring-like connecting member connecting each end of said sleeve to said support.
4. The burner of claim 3, wherein said connecting mem-ber is metal and is enclosed in a ring-like sleeve of woven ceramic material.
5. The burner of claim 1, wherein one end of said sup-port is provided with a circumferential groove, said sleeve being attached in said groove by said connecting means.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US58068684A | 1984-02-16 | 1984-02-16 | |
| US580,686 | 1990-09-10 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1241910A true CA1241910A (en) | 1988-09-13 |
Family
ID=24322120
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000472606A Expired CA1241910A (en) | 1984-02-16 | 1985-01-22 | Radiant energy burner |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS60228811A (en) |
| BE (1) | BE901744A (en) |
| CA (1) | CA1241910A (en) |
| DE (1) | DE3504601A1 (en) |
| FR (1) | FR2559877B1 (en) |
| GB (1) | GB2154312B (en) |
| NL (1) | NL8500365A (en) |
Families Citing this family (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4651714A (en) * | 1984-10-18 | 1987-03-24 | A. D. Smith Corporation | High efficiency water heater |
| US4721456A (en) * | 1986-05-08 | 1988-01-26 | A. O. Smith Corporation | Combustion element for a radiant energy burner and method of making same |
| AT393892B (en) * | 1987-07-10 | 1991-12-27 | Vaillant Gmbh | BURNER-HEATED BOILER |
| DE3918855A1 (en) * | 1989-01-21 | 1990-08-02 | Hydrotherm Geraetebau Gmbh | Controlled gas burner for heating boiler - has additional airflow provided by regulated blower to maintain programmed flame temperature |
| AT394053B (en) * | 1989-09-07 | 1992-01-27 | Voest Alpine Stahl Linz | GAS TRANSFER DEVICE FOR A COOKING OVEN |
| AT394768B (en) * | 1990-11-02 | 1992-06-25 | Chamottewaren U Thonoefenfabri | BURNER FLAME GUIDE PART |
| GB2258036B (en) * | 1991-07-23 | 1995-03-29 | Gazco Ltd | Gas fire burner |
| DE4324644A1 (en) * | 1993-07-22 | 1995-01-26 | Gossler Kg Oscar | Ceramic combustion carrier element for surface burner and method for its production |
| DE19521844B4 (en) * | 1994-06-24 | 2006-01-05 | Vaillant Gmbh | Burner for a gas-air mixture with outflow openings |
| AT401192B (en) * | 1994-06-24 | 1996-07-25 | Vaillant Gmbh | Burner for a gas/air mixture |
| AT404502B (en) * | 1994-06-24 | 1998-12-28 | Vaillant Gmbh | Burner |
| AT402229B (en) * | 1995-01-23 | 1997-03-25 | Vaillant Gmbh | Burner |
| US5520536A (en) * | 1995-05-05 | 1996-05-28 | Burner Systems International, Inc. | Premixed gas burner |
| DE102012000302B4 (en) * | 2011-09-23 | 2022-07-14 | Herbert Kannegiesser Gmbh | Device for heating a heat carrier, in particular for laundry machines |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1486796A (en) * | 1967-10-05 | |||
| US3269449A (en) * | 1964-09-21 | 1966-08-30 | American Radiator & Standard | Burner apparatus |
| US3439996A (en) * | 1965-06-09 | 1969-04-22 | Solaronics Inc | Tile assembly for radiant gas burners |
| FR1446140A (en) * | 1965-09-02 | 1966-07-15 | Infrared gas heater | |
| DE1955163A1 (en) * | 1969-06-14 | 1971-05-13 | Schwank Gmbh | Infra red source |
| FR2526919B1 (en) * | 1982-05-17 | 1987-05-22 | Osaka Gas Co Ltd | SURFACE COMBUSTION BURNER SUPPLIED TOTALLY WITH PRIMARY AIR |
-
1985
- 1985-01-22 CA CA000472606A patent/CA1241910A/en not_active Expired
- 1985-01-28 GB GB08502031A patent/GB2154312B/en not_active Expired
- 1985-02-08 JP JP2336785A patent/JPS60228811A/en active Pending
- 1985-02-09 NL NL8500365A patent/NL8500365A/en not_active Application Discontinuation
- 1985-02-11 DE DE19853504601 patent/DE3504601A1/en not_active Withdrawn
- 1985-02-14 FR FR8502101A patent/FR2559877B1/en not_active Expired
- 1985-02-15 BE BE0/214522A patent/BE901744A/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| GB2154312A (en) | 1985-09-04 |
| FR2559877A1 (en) | 1985-08-23 |
| GB8502031D0 (en) | 1985-02-27 |
| BE901744A (en) | 1985-05-29 |
| DE3504601A1 (en) | 1985-08-22 |
| JPS60228811A (en) | 1985-11-14 |
| FR2559877B1 (en) | 1989-10-20 |
| NL8500365A (en) | 1985-09-16 |
| GB2154312B (en) | 1987-08-12 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |